Because bacteria mutates that's why we have a new flu vaccine every year , because strains of DNA in the bacteria change all the time.
Answer:
This question lacks options, options are:
A.They maintain the cell’s shape.
B.They regulate cell processes.
C.They protect the body from infectious agents.
D.They signal the immune system to destroy pathogens.
E.They speed up biochemical reactions.
F.They send electrical signals.
The correct answers are C and D.
Explanation:
B cells and T cells use different biological weapons to attack the pathogen. The first secrete proteins called antibodies, which are distributed via the blood or the exposed surfaces to the environment, such as mucous. Antibodies are glycoproteins that circulate in the bloodstream looking for antigens that cause some type of damage to the body. Antibodies recognize and neutralize pathogens in a highly efficient way. Once the antibodies are produced, they remain circulating in the bloodstream for several months, which generates immunity for a long period of time to a certain antigen, in other words, they are capable of recognizing other molecules (antigens) in a very specific way and forming stable complexes with them (immune complexes). Its appearance in plasma is part of the adaptive immune response, in what is known as a specific humoral response, constituting a very effective defense against pathogens.
Different: in covalent bonds, atoms share electrons, whereas in ionic bonds atoms transfer electrons.
Alike: Both ionic and covalent bonding lead to the creation of stable molecules.
